diff --git a/tests/test-common.hpp b/tests/test-common.hpp
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+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2017, Regents of the University of California,
+ *                          Arizona Board of Regents,
+ *                          Colorado State University,
+ *                          University Pierre & Marie Curie, Sorbonne University,
+ *                          Washington University in St. Louis,
+ *                          Beijing Institute of Technology,
+ *                          The University of Memphis.
+ *
+ * This file, originally written as part of NFD (Named Data Networking Forwarding Daemon),
+ * is a part of ndncert, a certificate management system based on NDN.
+ *
+ * ndncert is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation, either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * ndncert is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License along with
+ * ndncert, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndncert authors and contributors.
+ */
+
+#ifndef NDNCERT_TESTS_TEST_COMMON_HPP
+#define NDNCERT_TESTS_TEST_COMMON_HPP
+
+#include "logging.hpp"
+
+#include "boost-test.hpp"
+
+#include <boost/asio/io_service.hpp>
+#include <boost/filesystem.hpp>
+#include <boost/filesystem/fstream.hpp>
+
+#include <ndn-cxx/name.hpp>
+#include <ndn-cxx/data.hpp>
+#include <ndn-cxx/lp/nack.hpp>
+#include <ndn-cxx/util/time-unit-test-clock.hpp>
+#include <ndn-cxx/util/string-helper.hpp>
+
+namespace ndn {
+namespace ndncert {
+namespace tests {
+
+/** \brief base test fixture
+ *
+ *  Every test case should be based on this fixture,
+ *  to have per test case io_service initialization.
+ */
+class BaseFixture
+{
+protected:
+  /** \brief reference to global io_service
+   */
+  boost::asio::io_service m_io;
+};
+
+/** \brief a base test fixture that overrides steady clock and system clock
+ */
+class UnitTestTimeFixture : public virtual BaseFixture
+{
+protected:
+  UnitTestTimeFixture();
+
+  ~UnitTestTimeFixture();
+
+  /** \brief advance steady and system clocks
+   *
+   *  Clocks are advanced in increments of \p tick for \p nTicks ticks.
+   *  After each tick, global io_service is polled to process pending I/O events.
+   *
+   *  Exceptions thrown during I/O events are propagated to the caller.
+   *  Clock advancing would stop in case of an exception.
+   */
+  void
+  advanceClocks(const time::nanoseconds& tick, size_t nTicks = 1);
+
+  /** \brief advance steady and system clocks
+   *
+   *  Clocks are advanced in increments of \p tick for \p total time.
+   *  The last increment might be shorter than \p tick.
+   *  After each tick, global io_service is polled to process pending I/O events.
+   *
+   *  Exceptions thrown during I/O events are propagated to the caller.
+   *  Clock advancing would stop in case of an exception.
+   */
+  void
+  advanceClocks(const time::nanoseconds& tick, const time::nanoseconds& total);
+
+protected:
+  shared_ptr<time::UnitTestSteadyClock> steadyClock;
+  shared_ptr<time::UnitTestSystemClock> systemClock;
+
+  friend class LimitedIo;
+};
+
+/** \brief create an Interest
+ *  \param name Interest name
+ *  \param nonce if non-zero, set Nonce to this value
+ *               (useful for creating Nack with same Nonce)
+ */
+shared_ptr<Interest>
+makeInterest(const Name& name, uint32_t nonce = 0);
+
+/** \brief create a Data with fake signature
+ *  \note Data may be modified afterwards without losing the fake signature.
+ *        If a real signature is desired, sign again with KeyChain.
+ */
+shared_ptr<Data>
+makeData(const Name& name);
+
+/** \brief add a fake signature to Data
+ */
+Data&
+signData(Data& data);
+
+/** \brief add a fake signature to Data
+ */
+inline shared_ptr<Data>
+signData(shared_ptr<Data> data)
+{
+  signData(*data);
+  return data;
+}
+
+/** \brief create a Link object with fake signature
+ *  \note Link may be modified afterwards without losing the fake signature.
+ *        If a real signature is desired, sign again with KeyChain.
+ */
+shared_ptr<Link>
+makeLink(const Name& name, std::initializer_list<std::pair<uint32_t, Name>> delegations);
+
+/** \brief create a Nack
+ *  \param name Interest name
+ *  \param nonce Interest nonce
+ *  \param reason Nack reason
+ */
+lp::Nack
+makeNack(const Name& name, uint32_t nonce, lp::NackReason reason);
+
+/** \brief replace a name component
+ *  \param[inout] name name
+ *  \param index name component index
+ *  \param a arguments to name::Component constructor
+ */
+template<typename...A>
+void
+setNameComponent(Name& name, ssize_t index, const A& ...a)
+{
+  Name name2 = name.getPrefix(index);
+  name2.append(name::Component(a...));
+  name2.append(name.getSubName(name2.size()));
+  name = name2;
+}
+
+template<typename Packet, typename...A>
+void
+setNameComponent(Packet& packet, ssize_t index, const A& ...a)
+{
+  Name name = packet.getName();
+  setNameComponent(name, index, a...);
+  packet.setName(name);
+}
+
+/** \brief convert file to digest
+ */
+ndn::ConstBufferPtr
+digestFromFile(const boost::filesystem::path& filename);
+
+} // namespace tests
+} // namespace ndncert
+} // namespace ndn
+
+#include "identity-management-fixture.hpp"
+
+#endif // NDNCERT_TESTS_TEST_COMMON_HPP